His successor, Jeff Edmunds, had been expected to be submitted for the leadership of the council at the authority’s annual general meeting on May 20.

But the independents, who had previously worked with Labour, refused to back the new leader, and instead turned to Plaid.

Plaid group leader Emlyn Dole will be nominated for election as leader of the authority at a council meeting next week.

'More open and transparent'

Labour had led the council in coalition with independent councillors since 2012.

Plaid councillor Alun Lenny said the party has its own manifesto and its own priorities and would be facing tough times ahead with the austerity measures from the UK Conservative Government imposed on the Welsh Government.

“Obviously we have inherited a most difficult position but we are determined to improve the image of the council and make it more open and transparent.”

But he said Plaid, whose first county councillor in Carmarthenshire was the late Gwynfor Evans, would do their utmost to protect the people of the county.

'Shabbily'

Mr Lenny said there was a feeling among councillors of all colours that Mr Madge had been treated “shabbily” by his Labour colleagues.

In a statement released on Tuesday Councillor Madge said it was with “deep regret” that he was standing down, but he did not refer to the decision made at the party’s AGM on Monday night.

Welsh language campaign group Cymdeithas yr Iaith described the move as “exciting”.

Sioned Elin, Chair of in Carmarthenshire said: “When the new leader is elected next week we will want to meet with him in order to make sure that the council’s Welsh Language Strategy is carried on as agreed last year, with the same cross-party backing.”